Exercise Sharpens Older Minds

A More Objective Measure of Physical Activity

In the second study, researchers used a more objective measure of energy expended during physical activity, employing the so-called doubly labeled water technique to determine how much water a person loses.

The study involved 197 men and women participating in the larger Health, Aging, and Body Composition study. Participants, whose average age was 75 years, had no mobility or cognitive problems when the research began.

Over the next two to five years, those in the highest third of energy expenditure were substantially less likely to develop clinical cognitive impairment than those in the lowest third.

Cognitive function was measured using the Mini-Mental State Exam (MMSE), a brief test of mental skills, including attention span and memory.

About 2% of people in the highest third suffered declines in cognitive function, compared with 5% in the middle third and 17% in the lowest third.

In a surprising finding, the participants' levels of energy expenditure did not completely correlate with how much physical activity they reported they did.

The results were reported by Laura Middleton, PhD, of Sunnybrook Health Sciences Centre in Toronto.

Exercise Good for Everyone

In an editorial accompanying the studies, Eric B. Larson, MD, MPH, of Group Health Research Institute in Seattle, said exercise "is definitely worthwhile" no matter what one's age and "is likely to be of increasing benefit as [one] advances into old age."

Ronald Peterson, MD, director of the Mayo Alzheimer's Disease Research Center at the Mayo Clinic in Rochester, Minn., tells WebMD that physical activity improves the flow of blood in the brain. Also, animal studies suggest that exercise may release enzymes into the brain that attach and destroy Alzheimer's-associated plaque, he says.